Expression

#include<iostream>
#include"stack.h"
using namespace std;

class Expression{
    Stack s;
public:
    int evaluate(char* str){
        char* temp = str;
        Stack s;
        while(*temp !='\0'){
            if(*temp>='0' && *temp<='9'){
                s.push(*temp-48);
            }
            else{
                int val1 = s.pop();
                int val2 = s.pop();
                switch (*temp)
                {
                    case '+': s.push( val2 + val1); break;
                    case '-': s.push(val2 - val1); break;
                    case '*': s.push(val2 * val1); break;
                    case '/': s.push(val2/val1); break;
                }

            }
            temp++;
        }
        return s.pop();
    }

    int precedence(char symbol){
        if(symbol=='+' || symbol == '-')
            return 1;
        else if(symbol=='*' || symbol == '/')
            return 2;
        else if(symbol=='^')
            return 3;
    }
    int isOperator(char ch){
        if(ch=='+' || ch=='-' || ch=='*' ||ch=='/'||ch=='^')
            return true;
        return false;
    }
    void conversion(char* str){
        char *temp = str;
        char ch;
        while(*temp!='\0'){
            if(*temp == '('){
                s.push(*temp);
            }
            else if(*temp>='0' && *temp<='9')
                cout<<*temp;
            else if(isOperator(*temp)){
                //cout<<"*temp: and "<<*temp<<" "<<s.counter()<<endl;
                if(s.isEmpty())
                    s.push(*temp);
                else if(s.StackTop()=='('){ //cout<<*temp<< "Pushed";
                    s.push(*temp);
                }
                else if(precedence(*temp) > precedence(s.StackTop())){
                    s.push(*temp);
                }
                else{
                    char ch = s.pop();
                    cout<<ch;
                    do{

                        ch = s.StackTop();
                        if(isOperator(ch) && (precedence(*temp)> precedence(ch)))
                            break;
                        ch=s.pop();
                        if(isOperator(ch))
                            cout<<ch;
                    }while((ch != '(') && !s.isEmpty());
                    s.push(*temp);

                }
            }
            else if(*temp ==')'){
                do{
                        ch = s.pop();//cout<<ch<<" EElements "<<s.counter()<<endl;
                        if(ch!='(')
                            cout<<ch;
                }while(!s.isEmpty());
            }
            temp++;
        }
        if(!s.isEmpty()){
           do{
                //cout<<"While "<<s.counter()<<endl;
            ch=s.pop();
            if(ch!='(')
                cout<<ch;//" elements "<<s.counter()<<endl;
        }while(!s.isEmpty());
    }
    }

};

int main(){
    cout<<"Welcome to linked implementation of Stack";
    Expression pe;
    char str[100];
    int choice=1;
    do{
        cout<<"Enter the Expression: "; //1+2*3
        cin>>str;                       //123*+
        pe.conversion(str);
        cout<<"Choice "<<endl;
        cin>>choice;
    }while(choice==1);
    return 0;

}